The child, tentatively identified as Boston Bramlage, 13, was found about 2:20 p.m. by officers from the Florida Fish and Wildlife Conservation Commission.

Polk County Sheriff Grady Judd said Friday that Boston was thrown from the plane through a gaping hole next to his seat.

He was found by FWC officers in treacherous terrain about four-tenths of a mile southwest of the main wreckage of the plane, Judd said. He said 100 law enforcement workers participated in the search.

Judd said airplane debris was scattered far and wide, but none near where Boston was found.

The crash occurred about 12:30 p.m. Thursday in a palmetto-covered clearing in the Tiger Creek Preserve on the southwest corner of Lake Walk-in-Water. The crash is the worst in Polk County's history, according to records from the National Transportation Safety Board, which date to 1962.

The pilot of the 12-seat Pilatus PC-12/47 turboprop was Ronald Bramlage, 45, a Kansas businessman. His wife, Rebecca Bramlage, 43, and their four children were on board. Their children are Brandon, Boston, Beau and Roxanne who range in age from 15 to 8.

The five bodies recovered Thursday were all in the aircraft, Judd said.

Investigators from the Federal Aviation Administration and the NTSB arrived at the site late Thursday and have begun their investigation, said Tim Monville, a senior air safety investigator for the NTSB.

"Our main goal is to determine what happened and why," he said.

Monville said Bramlage had been in contact with Miami air traffic controllers and had been flying at an altitude of 25,100 feet until the plane was lost from radar.

The plane left Treasure Cay Airport in the Abaco Islands, Bahamas, Thursday morning. It stopped at the St. Lucie County International Airport in Fort Pierce to clear customs and took off again at 12:05 p.m., headed for Kansas.

Another pilot in the area told investigators he had heard a mayday call from the plane, but the pilot was "not specific about the nature of the emergency," Monville said. A distress beacon in the plane activated and the plane was found a short time later in the rural field.

Monville will be working with NTSB's air traffic control office in Washington D.C., along with weather experts to determine if weather conditions affected the flight.

During the investigation, which could last between nine months and a year, NTSB officials will review maintenance records, pilot records, training records and toxicology tests. They also will reconstruct the aircraft.